It sounds unnatural, because the time clause says"something" and it should refer to an event or time. A thing is not a reference to time.. For example "I'll go to bed after something happens" or "I'll go to bed after a while"

That sounds right

try to be specific instead of using "something".. :)

It's good but instead of something use another word. For example "I'll go to bed after showering." Or I'll go to bed after dinner.